var UA = window.navigator.userAgent.toLowerCase()
var isIOS = UA && /iphone|ipad|ipod|ios/.test(UA)
if (isIOS) { // 如果是ios禁止用户缩放页面 android不用做限制
  window.onload = function () {
    document.addEventListener('gesturestart', function (e) {
      e.preventDefault();
    });

    document.addEventListener('dblclick', function (e) {
      e.preventDefault();
    });
    document.addEventListener('touchstart', function (event) {
      if (event.touches.length > 1) {
        event.preventDefault();
      }
    });
    var lastTouchEnd = 0;
    document.addEventListener('touchend', function (event) {
      var now = (new Date()).getTime();
      if (now - lastTouchEnd <= 300) {
        event.preventDefault();
      }
      lastTouchEnd = now;
    }, false);
  }
}